Still picture information recording medium and method and apparatus for reproducing still picture information therefrom

ABSTRACT

A technique is provided for reproducing information from a recording medium, on which there are recorded a plurality of picture information sets; presentation time values, each associated with a corresponding one of the picture information sets; picture information record marks, each of which is associated with a corresponding one of the presentation time values; clip information specifying what position on the recording medium is associated with each of the presentation time values; and reproducing order specifying information which specifies in what order the picture information sets are to be reproduced. Picture information is reproduced through the steps of detecting the presentation time value of a picture information set to be retrieved from the corresponding picture information record mark; using said clip information to detect the recording position on the recording medium which corresponds to the detected presentation time value; and reproducing picture information from the detected recording position.

BACKGROUND OF THE INVENTION

The present invention relates to a technique for recording/reproducingpicture information, in particular still picture information, on/from arecording medium.

FIG. 2 shows an example of the conventional arrangement of informationfiles that are stored on an optical disk, such as a DVD (DigitalVersatile Disc), where moving picture information is recorded. In theinformation file structure shown in FIG. 2, a directory DVR is formed onthe optical disk. Each information file is recorded under thisdirectory.

In FIG. 2, the info.dvr file 201 is a file where information such as thenumber and filenames of play lists under the DVR directory is written.The menu.tidx file 202 is a file where information such as the sizes andinformation amounts of thumbnails to be used in menus is recorded. Themenu.tdat file 203 is a file where thumbnail picture information to beused in menus is recorded. The mark.tidx file 204 is a file whereinformation such as the sizes and information amounts of thumbnailsassociated with mark positions are recorded. The mark.tdat file 205 is afile where thumbnail picture information to be used at mark positions isrecorded. Play list files 206 are files where marks and otherinformation specifying in what order and what parts of pictureinformation are to be reproduced are recorded. Clip information files207 are files where information such as play start points in streamfiles and their packet positions is recorded. Stream files 208 are fileswhere such packets as picture information and sound information arerecorded.

With respect to the stream files 208, picture information is compressedaccording to the MPEG2 standard, which is one of the standard pictureinformation compressing techniques, and the compressed information isconverted into a stream file before being recorded. MPEG2 provides anexcellent ability to compress a large amount of information not only toNTSC-format picture information, but also to HD (High Density) pictureinformation, such as Hi-Vision. The amount of information in originalpicture information can be compressed to about one tenth or onefiftieth. For example, picture information in the NTSC format iscompressed to about 6 Mbps, while HD picture information is compressedto about 20 Mbps. In both cases, MPEG2 can attain a sufficiently highpicture quality. Picture information compression by MPEG2 is widely usedin such applications as accumulation of picture information on DVDs anddigital broadcasting.

With respect to the clip information files 207, in the same manner asdescribed above, picture information is compressed according to theMPEG2 format before being recorded. The MPEG2 system compresses pictureinformation based on correlations between adjacent pictures. Morespecifically, if there are portions which do not change between adjacentpictures, information relating to these portions is not transmittedagain, and the last picture information received is used as it is forthese portions. However, this imposes a drawback in that not all pictureinformation elements can be reproduced by decoding such pictureinformation, only the changed portions of which were encoded. After suchan operation as fast forward or skip, play can be restarted only fromthose pictures in which all picture information elements were encoded.

Generally, when picture information compression is performed accordingto the MPEG2 standard, picture information is divided into groups, eachcomprising about fifteen pictures. Each of these groups is called a GOP(Group of Pictures). Play from the top of a GOP allows immediatereproduction of picture information.

In the clip information file 207, the packet position of the top of eachGOP is recorded with the time (corresponding to the Presentation TimeStamp value) indicating when its picture information was encoded. Thismakes it possible to easily find a play start position when a search orskip operation is performed.

Clip information files 207 are associated with stream files on aone-to-one basis. If a clip information file designated 01000.c1pi isrecorded in association with a stream file designated 01000.m2ts, thesefiles can easily be recognized as being associated with each other.

With respect to the play list files 206, information recorded in eachplay list file lists parts of stream files which are to be played in thespecified order. FIG. 3 more specifically shows the informationstructure of the play list files. In a play list file, theversion_number entry indicates the version of the play list. ThePlayList_start_address entry indicates where the play list informationis recorded in the play list file. The PlayListMark_start_address entryindicates where the play list mark information is recorded. TheMakersPrivateData_start_address entry indicates where the maker'sprivate information is recorded. Note that each play list containsinformation about one or more play items, indicating what parts ofstream files are to be played.

An example of, the play list mark information will be described indetail with reference to FIG. 7. The length entry indicates theinformation length of the play list mark information. Thenumber_of_PlayListMarks entry indicates the number of play list marks.The mark_type entry indicates the type of the play list mark. Themark_name_length entry indicates the length of the play list mark'sname. The ref_to_PlayItem_id entry indicates the number of the play itemassociated with the play list mark. The mark_time_stamp entry indicatesthe time when the play list mark was marked. The Entry_ES_PID entryindicates the packet ID of the ES (Elementary Stream) of the play itemassociated with the play list mark. The ref_to_thumbnail_index entryindicates the number of the thumbnail associated with the play listmark. The mark_name entry stores a character string representing thename of the play list mark.

An example of the stream management structure of moving pictureinformation will be described with reference to FIG. 13. As shown inFIG. 13, a stream is composed of plural titles and a title is composedof plural chapters. Each chapter is composed of plural scenes. In manycases, each scene is constituted by moving picture information that hasbeen recorded continuously until recording is stopped after having beenstarted.

With reference to FIG. 7 and FIG. 13, the types of play list marks willbe described. Each play list mark may have be any of one of severalidentifiable types; for example, a title mark indicates the top of atitle, a chapter mark indicates the top of a chapter and a skip markindicates the top of a scene.

With reference to FIG. 8, an example of how the play list information,play item information, clip information, stream files and play list markinformation are mutually associated will be described. Each play listincludes one or plural play items. In this example, two play items 802and 803 are shown a part of play list 801. Each play item specifies whatpart of what stream file is to be played by designating thecorresponding clip information's filename, STC_sequence number, starttime and stop time. More specifically, the play item 802 is associatedwith an area 804 of a stream file.

Each play item may be associated with a different stream file. Referencenumerals 806 and 807 respective indicate positions where play list marksare recorded. Actually, these play list marks are recorded in the playlist information and are converted to packet positions in the actualstream file by using the clip information. (For example, see JapanesePatent Laid-Open No. 2003-123389.)

The above-mentioned technique assumes that moving picture information isrecorded and reproduced using MPEG stream files. However, it isnecessary to record/reproduce still picture information as well asmoving picture information. In addition, unlike moving pictureinformation, when still picture information is to be reproduced, it isdesirable to allow each still picture to be accessed easily. Whenreproducing a plurality of still pictures from a recording medium, theuser is required to perform operations for such purposes as to switch tothe previous or next picture.

Since the recording/reproducing of still picture information is nottaken into consideration in the conventional recording and reproducingapparatus, however, the apparatus can not operate properly in responseto the above-mentioned operations by the user. In addition, a method fordisplaying still picture information while outputting sound informationcontinuously as BGM (Background Music) has not been taken intoconsideration.

It is an object of the present invention to solve the above-mentionedproblems, that is, to allow still picture information to be easilyselected and reproduced and to provide a user-friendly reproducingtechnique.

SUMMARY OF THE INVENTION

To solve the aforementioned problems, the present invention provides arecording medium on which the following information is recorded: aplurality of picture information sets; presentation time values, each ofwhich is associated with a corresponding one of the picture informationsets; picture information record marks, each of which is associated witha corresponding one of the presentation time values; and reproducingorder specifying information which specifies in what order the pictureinformation sets are to be reproduced.

In addition, the present invention provides a technique for reproducinginformation from a recording medium on which the following items arerecorded: a plurality of picture information sets; presentation timevalues, each of which is associated with a corresponding one of thepicture information sets; picture information record marks, each ofwhich is associated with a corresponding one of the presentation timevalues; clip information which specifies what position on the recordingmedium is associated with each of the presentation time values; andreproducing order specifying information which specifies in what orderthe picture information sets are to be reproduced. The pictureinformation is reproduced through the following steps: detecting thepresentation time value of a picture information set to be retrievedfrom the corresponding picture information record mark; using the clipinformation to detect the recording position on the recording mediumwhich corresponds to the detected presentation time value; andreproducing picture information from the detected recording position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a reproducing apparatus with which thepresent invention is carried out;

FIG. 2 is a diagram which shows an example of the structural arrangementof files on a recording medium;

FIG. 3 is a diagram which shows an example of the data structure of aplay list file;

FIG. 4 is a diagram which shows an example of the data structure of playlist information;

FIG. 5 is a diagram illustrating the information provided by atype_of_presentation entry;

FIG. 6 is a diagram which shows an example of the data structure of playitem information;

FIG. 7 is a diagram which shows an example of the data structure of playlist mark information;

FIG. 8 is a diagram which shows how information is mutually associatedwhen moving picture information is recorded;

FIG. 9 is a diagram which shows how information is mutually associatedwhen still picture information is recorded;

FIG. 10 is a diagram which shows how information is mutually associatedwhen BGM-combined still picture information is recorded;

FIG. 11 is a diagram which shows the format of a MPEG-TS;

FIG. 12 is a block diagram of an output timing control circuit; and

FIG. 13 is a diagram which conceptually shows an example of a streammanagement structure;

FIG. 14 is a diagram which shows how information is mutually associatedwhen still picture information is recorded; and

FIG. 15 is a diagram which conceptually shows the content of a play listfile.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is direction to a first embodiment of thepresent invention.

Although it is assumed in the description of this first embodiment thata DVD is being used as a recording medium, the present invention canalso be applied to the use of a CD (Compact Disc), MD (Mini Disc) andvarious other information recording media.

It is also assumed in the following description that intra framecompressed picture information (I pictures) is included in recordedMEPEG stream files (hereafter denoted simply as stream files) accordingto the MPEG2 standard. Needless to say, information can be encoded byanother picture information compression method as well.

Similar to picture information, sound information is compressed in termsof quantity by using a sound information compression technique in thisfirst embodiment. The employed sound information compression techniqueis selectable from a variety of compression systems, such as the MPEG1audio system and the AAC system that is used in BS digital broadcasting.In addition, since the amount of sound information is smaller than thatof picture information, it can be recorded by a linear PCM methodwithout compression.

In addition, in this first embodiment, picture information and soundinformation, which are encoded as described above, are multiplexed intoa stream file and recorded as a single file so as to facilitatetransmission and accumulation. More specifically, each information unitis converted into a 188-byte packet, which is given a PID (Packet ID) toidentify the packet. Giving a unique PID to each unit of informationallows packets to be sorted easily when they are reproduced.

In a first embodiment, not only picture and sound information, but alsosubtitle information, graphic information, control command informationand other information packets can also be multiplexed into a streamfile. Further, such packets as PMT (Program Map Table) and PAT (ProgramAllocation Table) packets, which define how PIDs are associated witheach other, and a PCR (Program Clock Reference) packet indicating timeinformation are also multiplexed. A stream file where information ismultiplexed in this way is recorded on an optical disk as a stream file.

A reproducing apparatus according to the present invention will bedescribed with reference to FIG. 1.

In FIG. 1, an optical disk 101 has information recorded thereon, and anoptical pickup 102 reads out information from the optical disk 101 byusing laser light. In a reproducing signal processing circuit 103, thesignal that has been read out through the optical pickup 102 issubjected to prescribed decoding processing, and it is converted to adigital signal. In an output control circuit 104, the digital signalfrom the reproducing signal processing circuit, where decodingprocessing was performed, is packetized according to a prescribedformat, and it is then subjected to output processing. A servo circuit105 controls the rotating speed of the optical disk and the position ofthe optical pickup 102. A drive control circuit 106 controls the servocircuit 105 and the signal processing circuit 103.

In an audio information decoder 107, a sound information signal isobtained by decoding sound information packets received from the outputcontrol circuit 104. An audio output terminal 108 outputs the soundinformation signal which was obtained through decoding by the audioinformation decoder 107. In a video information decoder 109, a pictureinformation signal is obtained by decoding picture information packetsreceived from the output control circuit 104. A video output terminal110 outputs the picture information signal which was obtained throughdecoding by the video information decoder 109.

On the optical disk 101, stream files are recorded, in which pictureinformation and sound information signal packets are multiplexed. Inaddition, such information as play list information, which lists itemsto be reproduced in the listed order from streams, clip information,which locates characteristic points in each stream, mark positioninformation, which indicates skip positions and chapter start positions,and menu information, that is used to select a play list, are recordedas files in a prescribed format.

Each play list information file has information about one or plural playitems, indicating what parts of what stream files are to be reproduced.

FIG. 4 shows an example of the data structure of the play iteminformation in the first embodiment. In the play item information, thelength entry indicates the length of the play items. Thetype_of_presentation entry indicates how the items are to be presented.The number_of_PlayItems entry indicates the number of play items in theplay item information. The number_of_SubPlayItems entry indicates thenumber of sub play items (Sub play items will be described later inconnection with a third embodiment.

FIG. 5 shows the meaning of the values which the type_of_presentationcan have. More specifically, if type_of_presentation entry is 0, theplay items are reproduced as ordinary moving or still pictureinformation. If the type_of_presentation entry is 1, they are reproducedas still picture information with BGM. Note that still pictureinformation with BGM will be described in detail later in connectionwith a third embodiment.

FIG. 6 shows an /example of the data structure of the play iteminformation. The length entry indicates the information length of theplay item. The still_flag entry is a flag indicating whether thepresentation is to be frozen at the end of the play item reproduced. Ifthe still_flag entry is set, the still_duration entry specifies inseconds how long the presentation is to be frozen at the end of the playitem being reproduced. When the entry still_duration=0, this specifiesthat the presentation is to be frozen infinitely. TheClip_Information_file_name entry represents the file identifier of thecorresponding clip information file and stream file. The ref_to_STC_identry indicates the sequence number of the STC in the stream file. TheIN_time entry specifies where the play item begins in the stream file bydesignating the corresponding PTS in the picture information. TheOUT_time entry specifies where the play item ends in the stream file bydesignating the corresponding PTS in the picture information.

In the first embodiment, play items are respectively associated withindividual still pictures, as shown in FIG. 14. On the other hand, asdescribed with the conventional technique, in the case of moving pictureinformation, it is not feasible to associate every I picture with a playitem since this tremendously enlarges the size of the play list file.Thus, play list mark information is recorded at the top of each chapter,as shown in FIG. 8. By using such marks, it is possible to realizevarious functions, such as to start reproduction from the next chapterand to go back to the top of the current chapter and start reproductiontherefrom. In the case of still picture information, however, it isdesirable to associate each still picture with a play item. Whenswitching to the previous or next still picture, this allows the stillpicture to be detected easily.

As described, in connection with the first embodiment, a plurality ofstill pictures can be recorded in such a manner that such operations asswitching to the next or previous picture can be implemented easily.

Now, a second embodiment of the present invention will be described.Although the description thereof is based on some assumptions, theseassumptions will not be specifically mentioned, since they are the sameas those made in the description of the first embodiment.

The second embodiment is characterized in that each still picture isassociated with a mark. That is, in the second embodiment, a stillpicture mark, which indicates the top of a still picture, is added asanother type of play list mark to the syntax shown in FIG. 7.Accordingly, each play list mark is recognizable, for example, as eithera chapter mark indicating the top of a chapter, a still picture markindicating the top of a still picture or a skip mark indicating the skipposition of a scene.

The meaning of each mark can be recognized if the mark is givenprescribed numbers assigned to the type of mark. This allows pluralmarks of the same type to be used selectively. Needless to say, it ispossible not only to give any meanings to marks, but also to use onlyone mark type.

In the second embodiment, if the position of each still picture isrecorded as a play list mark, it is possible to easily detect theposition of the objective still picture when switching to the previousor next still picture is to be performed. For reference, FIG. 15conceptually shows the play list management structure in the secondembodiment.

With reference to FIG. 9, an example of how each item of information isassociated when still picture information is recorded will be described.

When still picture information is recorded, it is recorded as pictureinformation instead of moving picture information. In the case of stillpicture information, picture information is not recorded continuously,but only where still picture information is to be reproduced. Meanwhile,such information as sound information and subtitle information isrecorded continuously on a stream whether the information is associatedwith still picture information or moving picture information.

Similar to moving picture information, the still picture information tobe recorded is picture information that has been compressed according tothe MPEG2 format and is recorded as a file in the form of a MPEGtransport packet. Unlike moving picture information, however, only oneintra frame compressed picture (I picture) is recorded as still pictureinformation. Since the information is terminated at the end of thepicture information, adding a sequence end code to the pictureinformation allows the decoder to display and hold one picture.

FIG. 11 conceptually shows a MPEG transport packet. The stream from theoutput control circuit 104 is output in the form of this MPEG transportpacket.

In FIG. 11, reference numeral 1101 designates a packet header and 1102designates a MPEG transport packet. The MPEG transport packet is 188bytes long. Plural consecutive packets, each with a 4-byte packetheader, are recorded as a stream file. Of the packet header, 30 bits areused as a time stamp and the remaining 2 bits are used as an area torecord additional information. The time stamp is used to control theoutput timing of the packet. Its value is determined by counting basedon a 27 MHz clock. FIG. 12 shows a specific example of a portion of theoutput control circuit 104 that is configured to control the packetoutput timing. The circuit portion includes an input terminal 1201, abuffer 1202, a time stamp pickup circuit 1203, an oscillator 1204, acounter 1205, a coincidence detector 1206 and an output terminal 1207.

The signal retrieved from an optical disk is supplied to the inputterminal 1201 of the output timing control circuit as a MPEG transportpacket. As shown in FIG. 11, this incoming MPEG transport packet has a4-byte packet header. The time stamp pickup circuit 1203 extracts a30-bit time stamp from the packet header of the MPEG transport packetand supplies it to the coincidence detector 1206. Concurrently, thepacket is stored in the buffer 1202.

Meanwhile, the oscillator 1204, which generates a clock signal having afrequency of 27 MHz, supplies this clock signal to the counter 1205. Thecounter 1205 is 30 bits long, the same as the time stamp, and it countsthe 27 MHz clock pulses. The result of the counting by the counter issupplied into the coincidence detector 1206.

An example of how reproduction is performed in a reproducing apparatusaccording to the second embodiment will now be described with referenceto FIG. 1.

On an optical disk 101, picture information streams, play listinformation, clip information, etc. are recorded in the aforementionedformats. Initially, the user sets the optical disk 101 into thereproducing apparatus. Once the optical disk is inserted, the drivecontrol circuit 106 detects the presence of the inserted disk and, bysending a signal, notifies the system control circuit 111 that a diskhas been inserted. Upon receiving the disk insertion signal, the systemcontrol circuit 111 reads out file management information from theoptical disk 101. More specifically, the system control circuit 111instructs the drive control circuit 106 to read out information from aprescribed sector of the optical disk 101. According to the instructionreceived from the system control circuit 111, the drive control circuit106 controls the servo circuit 105 to control the rotating speed andphase of the optical disk and the position of the optical pickup 102.Accordingly, the optical pickup 102 seeks out the specified sector andreads out information therefrom by laser light.

The laser light received by the optical pickup 102 is converted to anelectrical signal by a photoreceptive circuit, and the electrical signalis sent to the reproducing signal processing circuit 103. Thereproducing signal processing circuit 103 converts the electric signalto digital information by performing decoding, error correction and thelike on the signal. The information read out in this manner from theprescribed sector is sent back to the system control circuit 111 via thedrive control circuit 106. Based on the information received from thedrive control circuit 106, the system control circuit 111 analyzes thefile management information and the contents of the read out files. Therecorded file management information includes the directory, identifier,size and location of each file recorded on the optical disk 101. Usingthe file management information, the system control circuit 111 readsout the necessary files.

Then, the user instructs the reproducing apparatus to start playing theoptical disk 101. More specifically, the user pushes the play startbutton on a remote controller (not shown). The signal transmitted fromthe remote controller is received by the remote control receiver 112 andsupplied to the system control circuit 111. Recognizing the signal asthe play start command from the user, the system control circuit 111reads out a file info.dvr 201 to acquire the number, filenames, etc., ofplay list files recorded on the disk. The system control circuit 111displays the acquired play list information on the picture informationscreen, urging the user to select a play list. The embodiment may alsobe configured in such a manner that menu picture information isdisplayed with thumbnails.

The user selects a desired play list from the play lists displayed onthe TV picture information screen. This selection is effected by pushinga button, such as the upward, downward, rightward or leftward buttons onthe remote controller. Via the remote control receiver, the systemcontrol circuit is notified as to which button has been pressed. Ofcourse, this play list selecting operation is not necessary if the userintends to play the top play list.

Once a play list is selected, the system control circuit 111 reads outthe selected play list information from the optical disk. Each play listincludes a type_of_presentation entry, representing informationindicating how play is to be performed. It also includes play iteminformation indicating what parts of what stream files are to be playedby designating the corresponding filenames and play start and end times.In addition, play list mark information is also written. The play listmark information includes the numbers given respectively to the playitem and thumbnail associated with each marked time.

As example of how the reproducing apparatus operates when thetype_of_presentation entry is 0, that is, when ordinary play is to beperformed, will be described.

If the type_of_presentation entry is 0, files specified as play itemswill be played sequentially. More specifically, the system controlcircuit 111 reads out the top play item information and reads out a clipinformation file 207 associated with the Clip_information_file entrywritten there. Then, by using the clip information, the times designatedin the IN_time and OUT_time entries that are written for the play itemare converted to the corresponding packet start number and end number.Then, a stream file associated with the Clip_information_file entry isread out so as to replay it from the packet associated with the packetstart number. Retrieved stream packets are output from the outputcontrol circuit 104 to the audio decoder 107 and video decoder 109 atthe prescribed timings according to the time stamps written on thepackets.

In the audio decoder 107, sound information is decoded and output to thesound information output terminal 108. Similarly, in the video decoder109, picture information is decoded and output to the pictureinformation output terminal 110. In addition, subtitle information,graphic information and the like are decoded in prescribed decoders (notshown) and superimposed on the picture information signal to be output.Commands multiplexed into the stream are supplied from the outputcontrol circuit 104 to the system control circuit 111 where the commandsare interpreted.

The stream file is replayed until the packet which is given an endpacket number associated with the OUT_time entry for the play item 902is reached. After the end packet is replayed, the next play item 903begins to be replayed similarly. Once the play items listed in the playlist 901 all have been played, the reproducing apparatus goes back tothe play list selection stage. Needless to say, the system controlcircuit 111 may also be modified in such a manner that, in this case,the next play list begins to be played continuously.

An example of how the skip operation is treated while pictureinformation is being reproduced will be described.

As described earlier, play list mark information is included in the playlist 901. Each play list mark is associated with a play item andindicates the time when the mark was recorded. While the play item 901is being replayed, if the next chapter button on the remote controlleris pushed by the user to replay the next chapter, the play list markinformation associated with the current play item is read and a chaptermark 910 which exists later than the current replay time is retrieved asa skip mark.

In the description of the second embodiment, it is assumed that eachplay item corresponds to a chapter and that the top still picture markof each chapter serves also as a chapter mark, although this should notbe construed to limit the scope of the present invention. The presentinvention may also be implemented in such a manner that an arbitrarypicture group is associated with a play item and still picture marks areset separately from chapter marks. In addition, if another skip mark isnot found in the play list mark information associated with the currentplay item, the play list mark information associated with the next playitem may be searched.

The time of the chapter mark 910 that is retrieved in this manner isacquired from its mark_time_stamp entry and the corresponding play startpacket number is determined from the clip information. Then stillpicture information 905 begins to be reproduced from that packet. Thisallows the next chapter to be played in response to actuation of thenext chapter button.

Similarly, if the previous chapter button is pushed to restart replayfrom the next previous chapter, the play list mark informationassociated with the currently replayed item is read to find a skip markwhich is older than the current replay time. If there is no older skipmark in that play list mark information, the play list mark informationassociated with the next previous play item may be searched. The time ofthe skip mark retrieved in this manner is acquired from itsmark_time_stamp entry, and the corresponding play start packet number isdetermined from the clip information. Then the stream file begins to bereplayed from that packet. This allows the next previous chapter to bereplayed in response to actuation of the chapter button. In this way, astream can be replayed from before and after a play list mark position.

An example of picture information switching operations (skip, etc.) willbe described.

In FIG. 9, the play list 901 includes two play items 902 and 903. If theplay list 901 begins to be replayed, still picture information 904 andits accompanying information 907, such as sound information, included inthe play item 902, are replayed at first. The still picture information904 is immediately displayed if the stream begins to be replayed.Meanwhile, the accompanying information 907 is a stream having apredetermined length, and it is displayed over a predetermined period oftime (for example, 5 seconds). This replay period was determined whenthe information was prepared. After the play item 902 is replayed, theplay item 903 is replayed. The play item 903 includes two still pictures905 and 906, along with accompanying sound and other information 908. Ifthe play item 903 begins to be replayed, the still picture information905 is immediately displayed, and, after expiration of a predeterminedperiod of time, the still picture information 906 is displayed. Duringthis time, the accompanying information 908 continues to be output. Whenthe accompanying information 908 reaches to its end time, replaying theplay item 904 is completed.

If the next picture button is pushed to display the next still pictureinformation while the still picture information 905 is being replayed,the system control circuit retrieves the next picture mark 911 from theplay list mark information and begins to replay the stream from theposition given by the mark 911, that is, the still picture information906. The accompanying sound and other information 908 is multiplexedwith the still picture information stream. If the displayed stillpicture information changes, the accompanying information being outputalso changes. Accordingly, replay of the accompanying information 908 isrestarted from the position associated with the still pictureinformation 906, that is, the still picture mark 911 so that theremaining part of the accompanying information 908 is replayed.

Similarly, if the previous picture button is pushed to display theprevious still picture information while the still picture information905 is being replayed, the system control circuit picks up the nextprevious picture mark 909 from the play list mark information and beginsto replay the stream from the position given by the mark 909, that is,the still picture information 904 and accompanying information 907.

As described so far, the user can easily switch the displayed pictureinformation. In addition, the still_flag and still_duration entries canbe set to play items. They are used to freeze picture information for acertain period of time at the end of a play item that is being replayed.For example, the play item 902 will be frozen for 10 seconds at its endif the still_flag entry is set and the value 10 is assigned to thestill_duration entry. The system control circuit recognizes that thestill_flag entry is set for the play item 902 after the play item 902 isreplayed, and freezes the display. More specifically, the system controlcircuit stops the output of the sound information and continues todisplay the last picture information. Then, the system control circuitstarts replaying the next play item after 10 seconds have passed. Thus,the display can be frozen for an arbitrary period after play itemreplay. If the next picture button is pushed while the display isfrozen, replay may be restarted from the position of the next stillpicture flag. If the still_duration entry is set to 0, replay iscontrolled so as to freeze the display until some operation is performedby the user. This processing, combined with command processing, can beapplied to, for example, menu selection by the user.

As shown in FIG. 6, since the still_flag entry is set on an each playlist basis in the play list information structure of this embodiment,only the last picture information of each play item can be frozen. Toallow picture information during a play item replay to be frozen, theplay item must be divided into separate play items or the syntax must bemodified so that the still_flag and still_duration entry information canbe set more than once for each play item.

Note that, although the stream associated with the play list 912 in theexample of FIG. 6 has only still picture information and does notcontain sound and other accompanying information, the play list 912 alsoallows the same replay and skip operations as the play list 901. Inaddition, if every I picture of moving picture information is associatedwith a mark in the same manner as still picture information, switchingto another I picture can be performed easily when moving pictureinformation is displayed as still picture information.

As described so far, plural still pictures recorded in the secondembodiment can be easily switched to either display the next picture ora previous picture. Also, when moving picture information is displayedas still picture information, switching to either the next or theprevious picture can be performed easily.

A third embodiment of the present invention will be described withreference to FIG. 10. In the second embodiment described above, if thedisplayed still picture information is switched due to a skip operationor the like, the accompanying sound information is switched as well.However, it is preferable to continuously output sound informationwithout a break, for example, while a menu is being displayed forselection or while still picture information is being displayed like aphoto album. Accordingly, as shown in FIG. 10, BGM sound information isrecorded as a sub play item separately from the ordinary play items.FIG. 10 shows how information is mutually associated when BGM-combinedstill picture information is replayed.

If still picture information has been multiplexed with sound and otherinformation before being recorded, as shown in FIG. 9, switching thedisplayed picture information to another picture as instructed by theuser results in switching not only the picture information, but also theassociated sound and other accompanying information. This is not alwaysdesirable, for example, when a menu screen is to be displayed usingstill picture information. Accordingly, the third embodiment isconfigured in such a manner that even when picture information isswitched, sound information can be replayed continuously without abreak.

More specifically, as shown in FIG. 10, a play list includes not only aplurality of still pictures specified as ordinary play items, but alsosound information specified as a sub play item. Since this allows thesound information to be replayed independently of the still pictureinformation, the sound information can be replayed continuously evenwhen the displayed still picture is switched.

In view of the information syntax, a play item can be defined asBGM-combined still picture information by specifyingtype_of_presentation=1 in the play list information.

An example of how BGM-included information, as shown in FIG. 10, isreplayed will be described.

To replay still picture information with BGM, the entrytype_of_presentation is set to 1. In a play list 1001, a sub play item1010 is included with two play items 1002 and 1003. More specifically,the audio stream 1011 is specified as SubPlayItem() according to theinformation syntax in FIG. 6. Here, the stream corresponding to the playitems includes subtitle information, graphic information and controlcommands, as well as picture information, but does not contain soundinformation. Meanwhile, the sub play item stream 1011 contains onlysound information.

When the play list 1001 is to be replayed, information about the playitems (1002 and 1003) and the sub play item 1010 is acquired from theplay list (FIG. 4). Then, a clip information file is read out accordingto the Clip_information_file_name entry in the play item (FIG. 6). Usingthis clip file information, the stream replay start packet numberassociated with the time specified in the IN_time entry is obtained.Further, the stream file associated with the clip information file isread in to output and decode picture information starting from thepacket having the replay start packet number. The streams 1004, 1005 and1006 replayed here as play items include picture information andsubtitle information, but they do not contain sound information. Or,even if sound information is included, control is carried out so as toabort the sound information without outputting it. The play items in theplay list 1001 are replayed through this processing procedure.

Meanwhile, the sub play item 1010 is also specified in the play list1001. If the type_of_presentation entry is specified as 1 in the playlist information, the system control circuit in the reproducingapparatus judges that this play list includes the replay of stillpicture information with BGM. In this case, the sub play item is to betreated as BGM sound information. More specifically, a stream 1011corresponding to the sub play item 1010 is read in and control isperformed so as to repeatedly replay this stream. Of course, thiscontrol may be modified so as to replay the sub play item stream onlyonce. It is also possible to allow the number of times replay isrepeated to be specified/recorded for the sub play item. Note that thesub play item must be replayed concurrently with a play item. Forexample, time division processing makes it possible to read in andreplay/output both stream files concurrently. Of course, the same resultcan be obtained by reading the whole sub play item into a prepared largecapacity buffer memory in advance.

Then, on the assumption that the recorded information is structured asshown in FIG. 10, an example of how the replayed still pictureinformation is switched when instructed by the user will be described.

As described earlier, if the play list 1001 is selected, the play items1002 and 1003 will be replayed sequentially to output still pictureinformation. Concurrently, the sub play item 1010 will also be replayedto output sound information from the stream 1011.

If the next picture button is pushed by the user to display the nextstill picture while the stream 1005 is being replayed, the systemcontrol circuit retrieves the next still picture mark 1009 from the playitem marks and restarts replay at that position. Thus, the replayedstill picture information is switched to display the still pictureinformation contained in stream 1006. Meanwhile, the sub play item 1010continues to be replayed independent of the user's still pictureswitching operation. Thus, the stream 1011 can be replayed tocontinuously output sound information without a break even when thereplayed picture information is switched as instructed by the user.

The information structure shown in FIG. 10 also allows thestill_picture_flag and still_duration entry to be used to freeze thedisplay of each picture information for an arbitrary period after beingreplayed. Also, in this case, it is possible to prevent soundinformation from breaking if control is carried out so as tocontinuously output the sub play item 1010, i.e., the BGM soundinformation.

In the third embodiment, as described so far, by using a sub play itemas BGM sound information, it is possible to continuously output soundinformation even when the replayed image information is switched by theuser.

Note that, although in the specific example mentioned above, two typesof play list marks (chapter marks and still picture marks) areselectively used, this should not be construed to limit theimplementation of the present invention. It is also possible to use playlist marks of the same type. In this case, it is possible to performappropriate processing based on the result of judging whether thepicture information being replayed is ordinary moving pictureinformation or still picture information.

As described, in accordance with the third embodiment, a plurality ofrecorded still pictures can be easily switched to display either thenext picture or a previous picture. In addition, it is possible tocontinuously output sound information as BGM while still pictureinformation is displayed.

More particularly, the present invention makes it possible to easilyswitch reproduced still picture information and provides a user-friendlyreproducing technique.

Although the present invention has been described in terms of particularembodiments, other embodiments can also be implemented without departingfrom the spirit and scope of the present invention. The particularembodiments as described herein are merely examples and are not to beconstrued as limiting, in any way, the scope of the present invention.The scope of the present invention should be assessed in accordance withthe appended claims. Further, the scope of the present inventionencompasses all changes and modifications which are equivalent to thesubject matter of the appended claims.

1. An apparatus for recording information on a tangible recordingmedium, the information comprising: stream files including stillpictures; PlayList files which order still pictures and background music(BGM) to be played; and PlayListMarks that correspond to said stillpictures; wherein: each of said PlayList files has one or more PlayItemsand one or more SubPlayItems, each of said PlayItems corresponds to oneor more still pictures, each of said PlayItems includes startinformation indicating a presentation start time for the still picture,end information indicating a presentation end time for a still picture,and a presentation time of the still picture, each of said SubPlayItemscorresponds to a BGM, each of said SubPlayItems includes startinformation indicating a presentation start time for the BGM, endinformation indicating a presentation end time for the BGM, and apresentation time of the BGM, each of said PlayListMarks is associatedwith only one corresponding still picture, each of said PlayListMarks isprovided at a beginning of each of said PlayList files and at abeginning of each of said PlayItems, the still pictures of the PlayItemsand BGM of said SubPlayItems are independently reproduced and controlledwithout interrupting each other, reproduction of the BGM of theSubPlayItems is independently repeated, if there are additional stillpictures of the PlayItems to be reproduced, and one of a subsequent andlast PlayList file on the recording medium is played.
 2. The apparatusaccording to claim 1, wherein said start information is in the format ofIN_time and said end information is in the format of OUT_time.
 3. Anapparatus for recording information on a tangible recording medium, theinformation comprising: stream files including still pictures; PlayListfiles which order still pictures and background music (BMG) to beplayed; and PlayListMarks that correspond to the still pictures;wherein: each of said PlayList files has one or more PlayItems and oneor more SubPlayItems, each of said PlayItems corresponds to one or morestill pictures, each of said PlayItems includes start informationindicating a presentation start time for a still picture, endinformation indicating a presentation end time for a still picture, anda presentation time of the still picture, each of said SubPlayItemscorresponds to a BGM, each of said SubPlayItems includes startinformation indicating a presentation start time for the BGM, endinformation indicating a presentation end time for the BGM, and apresentation time of the BGM, each of said PlayListMarks is associatedwith one corresponding PlayItem and one still picture included in thecorresponding PlayItem, each of said PlayListMarks is provided at abeginning of each of said PlayList files and at a beginning of each ofsaid PlayItems, the still pictures of the said PlayItems and BGM of theSubPlayItems are independently reproduced and said still pictures arefreely changed (skip next or skip back) not interrupting thereproduction of said BGM, reproduction of the BGM of the SubPlayItems isindependently repeated, if there are additional still pictures of thePlayItems to be reproduced, and one of a subsequent and last PlayListfile on the recording medium is played.
 4. The apparatus according toclaim 3, wherein said start information is in the format of IN_time andsaid end information is in the format of OUT_time.
 5. An informationreproducing method for reproducing still picture information from arecording medium on which is recorded stream files including stillpictures, PlayList files which order still pictures and background music(BGM) to be played, PlayListMarks that correspond to said stillpictures, wherein each of said PlayList files has one or more PlayItemsand one or more SubPlayItems, each of said PlayItems corresponding toone or more still pictures and includes start information and endinformation, and each of said SubPlayItems corresponds to a BGM andincludes start information, end information, and presentation time forthe BGM, and wherein each PlayListMark is associated with only onecorresponding still picture and with only one corresponding PlayListfile and is provided at a beginning of each of said PlayList files andat a beginning of each of said PlayItems, said information reproducingmethod comprising the steps of: detecting said start information andsaid end information; controlling said presentation time of said stillpictures in accordance with said detected start information and endinformation; independently reproducing still pictures of the PlayItemsand BGM of the said SubPlayItems on one or more output devices, in whichsaid still pictures are freely changed (skip next or skip back) notinterrupting the reproduction of said BGM, independently repeatingreproduction of the BGM of the SubPlayItems, if there are additionalstill pictures of the PlayItems to be reproduced, and playing one of asubseguent and last PlayList file on the recording medium.
 6. Theinformation reproducing method according to claim 5, wherein said startinformation is in the format of IN_time and said end information is inthe format of OUT_time.
 7. An apparatus for reproducing informationrecorded on a tangible recording medium, the information comprising:stream files including still pictures; PlayList files which order stillpictures and background music (BGM) to be played; and PlayListMarks thatcorrespond to said still pictures; wherein: each of said PlayList fileshas one or more PlayItems and one or more SubPlayItems, each of saidPlayItems corresponds to one still picture, each of said PlayItemsincludes start information indicating a presentation start time for thestill picture, end information indicating a presentation end time forthe still picture, and a presentation time of the still picture, each ofsaid SubPlayItems corresponds to a BGM, each of said SubPlayItemsincludes start information indicating a presentation start time for theBGM, end information indicating a presentation end time for the BGM, anda presentation time of the BGM, each of said PlayListMarks is associatedwith only one corresponding still picture, each of said PlayListMarks isprovided at a beginning of each of said PlayList files and at abeginning of each of said PlayItems, the still pictures of saidPlayItems and BGM of said SubPlayItems are independently reproduced andsaid still pictures are freely changed (skip next or skip back) notinterrupting the reproduction of said BGM, reproduction of the BGM ofthe SubPlayItems is independently repeated, if there are additionalstill pictures of the PlayItems to be reproduced, and one of asubsequent and last PlayList file on the recording medium is played. 8.An apparatus for reproducing information recorded on a tangiblerecording medium, the information comprising: stream files includingstill pictures; PlayList files that order still pictures and backgroundmusic (BGM) to be played; and PlayListMarks that correspond to saidstill pictures; wherein: each of said PlayList files has one or morePlayItems, one or more SubPlayItems, and flag for type of presentationindicates playing with said SubPlayItem as BGM or not, each of saidPlayItems corresponds to one or more still pictures, each of saidPlayItems includes start information indicating a presentation starttime and end information indicating a presentation end time for a stillpicture, and each of said PlayItems indicates a presentation time of thestill picture, each of said SubPlayItems corresponds to a BGM, each ofsaid SubPlayItems includes start information indicating a presentationstart time and end information indicating a presentation end time forthe BGM, and each of said SubPlayItems indicates a presentation time ofthe BGM, each of said PlayListMarks is associated with only one ofcorresponding still picture, each of said PlayListMarks is provided at abeginning of each of said PlayList files and at a beginning of each ofsaid PlayItems, the still pictures of said PlayItems are independentlyreproduced while said BGM of said SubPlayItem is reproduced on the oneor more output devices when the flag for type of presentation indicatesplaying with said SubPlayItem and said still pictures are freely changed(skip next or skip back) not interrupting the reproduction of said BGM,reproduction of the BGM of the SubPlayItems is independently repeated,if there are additional still pictures of the PlayItems to bereproduced, and one of a subsequent and last PlayList file on therecording medium is played.